The proposed studies will be directed towards elucidating mechanisms of trophic interactions between motor nerves and skeletal muscle; learning more about sprouting and regeneration of peripheral nerves; and studying the mechanisms of neuromuscular disorders including myasthenia gravis. We will carry out studies of the effects of blockade of various components of cholinergic transmission on several properties of muscle that are regulated by nerves. We will explore the appearance of new virus receptors on denervated skeletal muscles. Finally, we will examine various aspects of humoral and cellular immune mechanisms in myasthenia gravis in man and animals, and attempt to devise rational therapeutic approaches.